java code: byte b[] = encrypt(plain.getBytes(charset), ByteFormat.hexToBytes(hexKey)); return ByteFormat.toHex(b);

Encrypted data is not the same as PHP.

This library seems incompatible with Arduino XXTEA. The application was to send an encrypted data from Arduino via POST request and decrypt it in PHP. Arduino XXTEA used

The two libraries decode in different ways it seems.

Look at the picture below, you see how the ecrypted string in Arduino is d49baa5e4b9b6ee6c8cf5ab0a61baa7a But the encrypted string in PHP xxtea is a bounch of awful stuff: ,„'—ÍÌIˆ(¦HLìF0do Look at the screenshot, on the right there is the Arduino serial monitor encrypting with its XXTEA and on the left PHP encrypting with your XXTEA

Maybe converting those buch of waful stuff from HEX to string I can have a result.

Here is are some results with XXTEA/PHP:

text:    This is an example. !@#$%^&*(){}[]:;
key:     8GmZWww5T97jb39W
encrypt: ZB3oHyOnV+jeZlS4JzQYxwiToxy0NYbcV7YN8wPDHsNLTjxJGPr+5w==
decrypt: This is an example. !@#$%^&*(){}[]:;

Encryption does not match the results for XXTEA/JavaScript:

text:    This is an example. !@#$%^&*(){}[]:;
key:     8GmZWww5T97jb39W
encrypt: BPAOskr9QeOE9S2gtKrArurP5RtjM+5GzQF6gLB4BKi+HAJV
decrypt: This is an example. !@#$%^&*(){}[]:;

Hi, i have a fix to suggest : In the function mx(), in my server, i had an issue with right byte shifting in $y >> 3 because it returned negative values. For fixting it : (from http://stackoverflow.com/questions/2642026/php-equivalent-javascript-shift-right-with-zero-fill-bitwise-operators )

private static function rightShift($x, $c)
          {
              $x = intval ($x); // Because 13.5 >> 0 returns 13. We follow.
              $nmaxBits = PHP_INT_SIZE * 8;
              $c %= $nmaxBits;
              if ($c)
                  return $x >> $c & ~ (-1 << $nmaxBits - $c);
              else
                  return $x;
          }

then replace eveywhere you use x << y

This is my local test, which data_x represents how much megabits to be encrypt. I generated from 1 to 100 megabits to data directory, below is some test results. It's used huge memory and time to encrypt data.

test tools https://github.com/Svish/TimerPHP /my/path/to/test_xxtea/test_xxtea.php() │ │ 78.502 s │ 6.58 KiB, 1.14 GiB │ ├ test_encrypt() │ │ │ │ 78.502 s │ │ 5.86 KiB, 1.14 GiB │ │ │ ├ test_encrypt(data/data_10) │ │ │ │ │ │ 12.831 s │ │ │ 1.44 KiB, 855.50 MiB │ │ ─┘ │ │ │ ├ test_encrypt(data/data_11) │ │ │ │ │ │ 14.563 s │ │ │ 160.00 B, 934.50 MiB │ │ ─┘ │ │ │ ├ test_encrypt(data/data_12) │ │ │ │ │ │ 15.647 s │ │ │ 144.00 B, 1013.50 MiB │ │ ─┘ │ │ │ ├ test_encrypt(data/data_13) │ │ │ │ │ │ 16.984 s │ │ │ 144.00 B, 1.07 GiB │ │ ─┘ │ │ │ ├ test_encrypt(data/data_14) │ │ │ │ │ │ 18.477 s │ │ │ 144.00 B, 1.14 GiB │ │ ─┘ │ ─┘

test_xxtea_script.php

<?php
include 'Xxtea.class.php';
include 'Timer.php';

function p($message = '', $tag = 'debug') {
    echo '['. $tag .']'. " ". $message ."\n";
}

function generateData($meta=1)
{
    // 1024
    $str = str_repeat(str_repeat('y', pow(2, 10)), $meta*1024);
    $file_name = 'data/data_'.$meta;
    file_put_contents($file_name, $str);
    p("generate ".$meta." M data to ".$file_name, 'generate data');
    unset($str);
}

function test_encrypt($start, $end) 
{
    Timer::start('test_encrypt');
    for($i = $start; $i < $end; $i++)
    {        
        $file_name = "data/data_".$i;
        p($file_name, 'before encrypt');
        Timer::start("test_encrypt", [$file_name]);      
        $encrypt_data = null;    
        if (file_exists($file_name))
        {
            $encrypt_data = xxtea_encrypt(file_get_contents($file_name));
            file_put_contents("data_enrypt/data_".$i."_enrypted", $encrypt_data);
        }
        unset($encrypt_data);
        p($file_name, 'after encrypt');
        // Sub section stuff
        Timer::stop();
    }
}
$start = 10;
$end = 15;
Timer::start($_SERVER['PHP_SELF']);
test_encrypt($start, $end);
Timer::stop();
echo $result = Timer::result();
file_put_contents("result_".$start."_".$end.".txt", $result);